1. Field of the Invention
The present invention relates to a motor.
2. Description of the Related Art
Brushless motors have been installed in a variety of devices, including, for example, vehicle transmissions. JP-A 2007-187262, for example, discloses a conventional brushless motor installed in a transmission of a vehicle.
An electric actuator disclosed in JP-A 2007-187262 includes an electric motor (a brushless motor) and a ball screw mechanism arranged within a rotor magnet and defining a portion of the electric motor. The electric motor is arranged to rotate based on instructions received from a control system (e.g., an ECU) of the vehicle. The ball screw mechanism is arranged to convert a rotational motion of the rotor magnet into a straight linear motion. Since the ball screw mechanism is arranged within the rotor magnet, noise that accompanies the converting operation of the ball screw mechanism is kept within the electric motor.
As described above, the conventional brushless motor disclosed in JP-A 2007-187262 is used in the vehicle, such as an automobile, and is required to operate stably under a variety of environments. A gear shift device installed in the transmission, for example, will often increase in temperature up to more than one hundred and ten degrees centigrade due to heat generated in an engine, frictional heat generated in the gear shift device, and the like. Therefore, a brushless motor installed in the gear shift device is required to operate stably under the aforementioned high temperature environment.
However, in the case of a brushless motor in which end portions of conductor wires defining coils are connected with busbars with solder, the aforementioned high temperature environment may cause the solder connecting the coils to the busbars to be melted. This will cause the brushless motor to be inoperative, leading to impaired reliability of the brushless motor.